During surgical procedures, bits of suture, i.e. surgical threads or ligatures are used to loop around or pass through body structures. The ligature bit may be passed around the structures in a single turn or multiple turns or in the configuration of other known bends and hitches. These ligatures, for example, are then tied around a blood vessel to constrict it and stop bleeding permanently, pulled to constrict the blood vessel or retract the structure, or tied to bind or hold the parts together. Two ligature bits may be passed alongside to each other looping around the structure and the respective limbs of the ligature tied together and subsequently the structure may be divided in between the tied ligatures. Sutures are made of different materials, thickness and qualities and commercially available either fastened to a needle for sewing tissue, or free of needles. Suture, not attached to needles is mostly used for looping or ligation of structures and is packaged wrapped either on a spool or as bits of predetermined standard length.
Similarly, ligatures or cords are also required in various non-surgical procedures.
It is most important to perform every surgical operation safely without any complications, economically, and speedily as extra time spent during surgery increases the operating cost and endangers the life of the patient.
The Conventional Surgical Technique of Ligation and its Drawbacks
The ligation of a structure for example a vein is done conventionally with the following drawbacks:
1. Bits of surgical suture are procured from commercially available packets or bits of ligature are precut from a reel at the start of the operation by the scrub nurse, going by a rough estimate of the ligature requirement. This wastes time and suture material as the nurse arbitrarily tends to cut long bits of the ligature to suffice diverse purposes. Similarly commercially packaged sutures are of predetermined lengths and are generally longer than required as they are intended to suit diverse purposes.
2. The vein to be ligated is dissected using blunt or sharp instruments and freed from the adjoining structures at the site of ligation creating an adequate space for the subsequent passage of the instruments and the ligature. This wastes time, requires special instruments and is liable to injure the vein and adjoining structures.
3. The surgeon takes a curved or a right-angle surgical clamp and with the jaws closed, the tip of the clamp is passed behind, from one side of the vein, to the extent that the tip is visible on the other side of the vein. The clamp can cause injury to the structures during passage.
4. The jaws of the clamp are opened apart proportional to the thickness of the ligature and the clamp is held in this position. The vein or the adjoining structure may be damaged.
5. One end of the ligature bit held with a forceps by the assistant is positioned within the opened jaws of the clamp. Requires another instrument and assistance.
6. The surgeon to grasp the end of the ligature closes the jaws of the clamp and the clamp is withdrawn back from behind the vein, thus pulling the ligature and forming a ‘U’ loop around the vein with two equal limbs, on either side of the vein. Before the ligature is pulled around the vein, a suitable fluid is applied to the ligature to decrease the drag on the vein and adjoining structures. Along with the ligature, the wall of the vein or the adjoining structures may be inadvertently caught in the clamp and damaged. The ligature when drawn around the vein is in direct contact with the vein and the adjoining structures and thereby grazes and drags on these structure with a sawing action which requires the ligature to be moistened with a fluid and in spite of the lubrication can still injure the structures.
7. The clamp is removed and the two limbs of the ligature loop are tied in a knot.
8. Proximate to the knot the two limbs of the ligature loop are cut off and discarded. Only a short length of the ligature is actually consumed in the knot, nevertheless, extra length of the suture bit is still required to manipulate and tie the ligature into a knot. Once the knot is tied, the two limbs of the ligature loop are cut off beyond the knot and because of their resultant short lengths—less than half of the original ligature—cannot be used for more ligations and hence discarded. This leads to wastage of expensive sutures.
9. For a more secure ligation, it is often necessary to deploy the same ligature around the vein in more than one turn. To do so requires the repetition of the above-mentioned steps. The clamp is once again passed under the vein in the same direction as in step 3.
10. The end of the ligature limb of the first ‘U’ loop on the same side of the clamp is crossed over in front and to the opposite side of the vein and grasped in the clamp and is looped around the vein in a second turn by withdrawing back the clamp, as in the abovementioned point 6 eventually looping the same ligature twice around the vein. When grasping and pulling the ligature end a second time not only the vein and the adjoining structure but the first loop of the ligature passing behind the vein may also be grasped and may completely avulse the vein.
11. It is often necessary to divide the vein and this is done by tying two ligatures alongside by repeating the above steps twice and then dividing the vein in between the two ligatures. The ligatures are tied sequentially and not simultaneously, which is time consuming.
12. If the ligature must be passed through a structure than expensive suture with a pre-fastened needle has to be used, or the ligature is passed through an eye needle and used, which is time consuming Moreover, the needle has to be mounted on a needle holder, which requires an additional instrument and more time.
13. It is difficult to perform ligation through the confines of the narrow endoscopic ports during endoscopic surgery, even with the use of endoscopic instruments.